This invention relates to a fluid distributor-collector or a fluid distributing-collecting system that is used, for example, in a device for bringing fluids and solids into contact.
The invention can be applied in particular in the area of chromatography for fluids in a gaseous state, liquid state or supercritical state.
The invention relates to a distributing-collecting system that can be used in a separation process in a simulated moving bed of paraxylene that is contained in a mixture of xylenes and ethylbenzene, for the purpose of terephthalic acid synthesis, an intermediate petrochemical product in the production of textiles.
The invention can also be used in processes for separating, for example, a xylene and ethylbenzene isomer mixture, a mixture of a compound that is selected from saturated fatty acids and their esters, a mixture of paraffin and olefins, a mixture of isoparaffins and normal paraffins, and other compounds.
The device according to the invention can operate in a liquid phase, a vapor phase or in a supercritical phase and in all of the separation areas of chemistry, petrochemistry or petroleum, for example.
In the area of separation processes, it is customary to rely on simulated moving bed systems to separate the elements that comprise, for example, at least two different chemical compounds or else two isomers of the same compound. The adsorption material that is used is, for example, a solid.
The technological background that illustrates the implementation of an adsorption device with simulated countercurrent is described in, for example, U.S. Pat. No. 2,985,589.
In these processes, a main fluid that is introduced via a pump flows through the solid bed along the central axis of the column. To obtain the best performances of this process, it is important that the main fluid flows through the adsorbent according to a piston-type flow (plug flow) to have a composition and a flow front that are the most uniform possible at all points of the surface of the adsorbent bed.
For this purpose, the prior art describes various means that attempt to obtain and to maintain such a flow.
The device that is described in U.S. Pat. No. 3,523,762 that is arranged between two adsorbent beds makes it possible to remix the fluid while flowing.
For applications with simulated countercurrent, the device that is described in U.S. Pat. No. 3,214,247 shows a structure that comprises an upper grid, a lower grid for holding particles and two non-perforated horizontal baffles that are positioned between these two grids. The fluids are added or extracted from a central space between the deflectors via a hose that traverses the entire section of the device. Such a device makes it possible to remix the fluid while flowing in the column and also to ensure a good mixing of a fluid that is added to the main fluid.
It is also possible to mention the two patents U.S. Pat. No. 5,792,346 and U.S. Pat. No. 5,755,960 that describe fluid distribution panels or DME whose function in particular is to mix, extract or add fluids. These DME are connected to fluid distributing-collecting circuits that seek to homogenize the passage time of the particles of the fluid from outside of the column to the panels and conversely from a panel to an outside collecting network.
Actually, the dispersion into the composition of the flow and in the passage time of the fluid particles can also be obtained in the way in which the fluids are distributed or extracted up to the DME or from the DME.
Some distributing or collecting circuits are designed for reducing the dispersion time of the fluids. The geometry of these circuits is generally adapted to the geometry of the plates and to the arrangement of the DME at these plates.
For example, in U.S. Pat. No. 5,792,346, the circuit for distributing or extracting secondary fluids shows a distribution symmetry and an isolength of the transfer lines of the fluids. These circuits allow a distribution of the separator-type fluids or a radial distribution from or to the center of the separation column.
In U.S. Pat. No. 5,755,960, the distributing-collecting circuit consists of several radial hoses that comprise several branches for distributing or collecting secondary fluids to or from each panel that forms a distribution plate. The branches are distributed over the whole or over a portion of the length of the radial-feed hose to which they are connected. Another variant consists in distributing the fluids from a ring or half-rings that are positioned on the periphery of the column. The fluid transfer hoses up to a DME are distributed over the entire length of the ring or half-rings.
Patent EP-074,815 describes a system for distributing fluids inside a device for bringing fluids and solids into contact that comprises several fluid distributing rings. The rings are mounted on a central tube of the device and arranged between adjacent levels of fluid distributor plates. Several distribution pipes that extend between a fluid distributor plate and the distribution ring make possible the injection and/or collection of fluid.
All of these systems meet the need of obtaining a piston-type flow or xe2x80x9cplug flowxe2x80x9d inside of a device for bringing it into contact to minimize the passage times of fluids so that they arrive virtually at the same time in the different panels of the same plate.
The object of this invention relates to a fluid distributing-collecting system that in particular makes it possible to obtain and to maintain a plug flow, a homogeneity of the composition of this flow, and to minimize the dispersion time of the fluids that are injected or extracted in the panels that form a distribution plate.
Throughout the rest of the description, a level 1 chamber is defined as a chamber whose function is to divide a fluid at least in two or to collect two fluid flows, and a level 2 chamber is defined as a chamber that ensures the division at least in two of a fluid that is obtained from a level 1 chamber or the collection of at least two fluid flows to send them to a level 1 chamber.
The term DME refers to a panel whose function in particular is to collect, mix, extract or remix one or more fluids.
This invention relates to a fluid distributing-collecting system for a device for bringing fluids and solids into contact, whereby said device comprises a chamber, at least one hose for introducing a main fluid and at least one hose for evacuating the main fluid, several distributor plates (Pn), whereby each of said plates comprises several panels for mixing, distributing or extracting fluids or DME. It is characterized in that it comprises:
at least one hose that makes it possible to link said device and the outside,
at least one chamber (N1) that is linked with said hose or hoses,
one or more connecting hoses C(N20)j, C(N21)j, that link the chamber and at least one of the DME of a plate (Pn), whereby connecting points rj of said hoses are located in a zone (Z20, Z21), whereby the positioning of said zone is determined by an angle xcex1 counting from one of the radial axes of said plate (Pn), whereby each of the connecting hoses has a length li, whereby the value of each of lengths li, of angle xcex1 and of length Zr of the zone are selected so that the passage time of the fluids between a panel (DME) and hose or hoses (1, 2) is essentially identical for all of the fluids.
The chamber ensures, for example, the division of the fluid into at least two flows.
According to an embodiment, the distributing-collecting system comprises, for example:
at least one level 1 chamber (N1) that ensures a two-way division or collection of the fluid flow, whereby chamber (N1) is linked with the hose or hoses,
at least one so-called level 2 chamber (N20, N21), whereby the chambers ensure a two-way division or collection of the fluid flow that comes from or is sent to chamber or chambers (N1),
one or more connecting hoses (C(N20)j, C(N2,)j that extend between at least one level 2 chamber (N20, N21) and at least one of the DME of a plate (Pn), whereby connecting points rj of the hoses are located in a zone (Z20, Z21), whereby the positioning of the zone is determined by an angle xcex1 counting from one of the radial axes of plate (Pn), whereby each of the connecting hoses has a length li, and whereby the value of each of lengths li, angle xcex1 and length Zr of the zone are selected so that the passage time of the fluids between a panel (DME) and the hose, or hoses, is essentially identical for all of the fluids.
Angle xcex1 is, for example, between 30 and 90 degrees, preferably between 50 and 60 degrees, and length Zr for a zone that corresponds to angle sector xcex1+/xe2x88x92xcex5 is between 3 and 30 degrees and preferably between 7 and 15 degrees.
This invention also relates to a device for bringing fluids and solids into contact that comprises a chamber that comprises an outside wall, at least one hose for introducing and at least one hose for extracting a main fluid, several hoses for introducing or extracting secondary fluids, several spaced levels of plates (Pn), whereby each plate (Pn) comprises one or more distributing-mixing-extracting panels (DME) of secondary fluids and a main fluid, at least one fluid distributing-collecting system, characterized in that:
said distributing-collecting system is arranged on the periphery of the chamber,
said distributing-collecting system is connected with at least one distribution plate (Pn),
said system comprises:
at least one hose that makes it possible to link the device and the outside,
one or more level 1 chambers (N1) that ensure a two-way division or collection of the fluid flow,
one or more level 2 chambers (N20, N21), whereby the level 2 chambers ensure a two-way division or collection of the fluid flow that comes from or is sent to level 1 chamber (N1)
connecting hoses (C(N20)j, C(N21)j) that extend between a level 2 chamber (N20, N21) and at least one of the panels (DME) of a plate (Pn), whereby the connecting points of the connecting hoses are located in a zone (Z20, Z21), whereby the positioning of this zone is determined by an angle xcex1 counting from one of the radial axes of a plate (Pn), whereby each of the fluid connecting hoses has a length li, and the value of each of lengths li, angle xcex1 and length Zr of the zone are selected so that the passage time of the fluids between a panel (DME) of a plate (Pn) and the hose for introducing or extracting fluids is essentially identical for all of the fluids.
Angle xcex1 can be between 30 and 90 degrees, preferably between 50 and 60 degrees, and length Zr that corresponds to the angle sector is between 3 and 30 degrees and preferably between 7 and 15 degrees.
According to a variant embodiment, the device comprises at least one plate that comprises at least one DME that has the following characteristics:
at least one means for collecting a main fluid,
at least two injection and/or draw-off rails that allow the passage of secondary fluids that are each provided with openings, whereby the rails are arranged one on top of the other,
at least two mixing chambers that are provided with openings, whereby the chambers are arranged on both sides of at least one of the rails and relative to the openings,
means for distributing the fluid that is obtained from the mixing chamber,
means for separating said collecting and distributing means.
Each plate (Pn) can be divided into several panels or DME according to a cutaway in parallels.
A plate can be divided into four sectors.
The upper rail has, for example, a function of collecting fluids, and the lower rail has a function of injecting fluids.
The upper rail may have a function of injecting fluids, and the lower rail may have a function of collecting fluids.
According to another variant embodiment, the upper and lower rails have a fluid injecting-collecting function.
The openings of the injection rail or rails are arranged such that the fluid jet that passes through strikes at least one portion of a solid wall of one of the mechanical elements of the DME.
The openings can be arranged alternately or at random.
The openings of the injection and/or draw-off rails are defined with, for example, the following parameters:
a diameter of between 2 and 15 mm and preferably in the range of 4 to 7 mm,
a perforation span of between 25 and 400 mm and preferably between 50 and 200 mm,
a rate of flow of the fluids of between 3-20 m/s and preferably between 5-15 m/s; the value of the span that is under consideration with the value of the rate makes it possible to obtain a good mixing of the secondary fluid and the main fluid.
The openings of the mixing chambers have, for example, the following characteristics:
a diameter of between 10 and 25 mm, and preferably between 5 and 50 mm,
a perforation span that is selected from the interval 50-200 mm and preferably in the interval of 25-400 mm,
a rate of flow of the mixture of between 1.0 and 2.0 m/s and preferably between 0.5-3.5 m/s.
This invention also relates to a process for separating at least one compound from a mixture or an element by adsorption.
It is characterized in that a main fluid, from which it is sought to separate some compounds, is brought into contact with an adsorbent that is selected as a function of its ability to separate the compounds, and the secondary fluids are injected and/or extracted via one or more distributing-collecting systems.
It is possible to group the fluids by function (injection/or draw-off) or by nature or by flow rate value.
The system, device and the process according to the invention pertain to the separation of a feedstock by chromatography for fluids in a gaseous state, liquid state or supercritical state.
They can also pertain to the separation of paraxylene in a simulated moving bed.
The device according to the invention has in particular the following advantages:
because of the good distribution symmetry of the secondary fluids and the main fluid, the mixture that is produced is improved over the entire plate, which imparts a more homogenous composition and a general plug flow to the circulating flow in the separation device,
to optimize the mixing of fluids inside the distribution panels, mixing, extraction, to remix the main fluid while flowing,
to reduce the time dispersion of the injection of fluids or the extraction of fluids to or from various panels that constitute a distribution plate.